AI 中文总结
研究长链支化聚合物熔体非线性振荡响应，提出分子管理论，纳入分支点力传递和延迟臂回缩，解释NLI特征最大值，预测不同非线性区域及相关参数，为非线性傅里叶流变学提供分子解释并联系聚合物结构。
AI 中文摘要
长链支化通过引入线性聚合物中不存在的臂回缩途径，深刻地改变了缠结聚合物熔体的非线性振荡响应。我们提出了一种分子管理论，该理论解释了在长链支化聚合物中实验观察到的非线性指数（NLI）的特征最大值。该理论通过纳入分支点力传递和延迟臂回缩，扩展了最近发展的线性聚合物的非线性管取向描述。主链最初像相应的线性聚合物一样发展非线性取向，而长臂回缩随后放松储存的分支点张力，并逐渐消除主链取向记忆。这种竞争产生了一个特征性的NLI最大值，随后是峰值后衰减。该理论预测了对应于稀疏和密集长链支化的两个不同的非线性区域，并引入了一个控制非线性峰值高度和宽度的结构参数。由此产生的框架提供了非线性傅里叶流变学的分子解释，并将非线性谐波响应与聚合物结构直接联系起来。
英文摘要
Long-chain branching profoundly modifies the nonlinear oscillatory response of entangled polymer melts by introducing arm-retraction pathways absent in linear polymers. We present a molecular tube theory that explains the characteristic maximum of the Nonlinearity Index (NLI) observed experimentally in long-chain-branched polymers. The theory extends the recently developed nonlinear tube-orientation description of linear polymers by incorporating branch-point force transmission and delayed arm retraction. The backbone initially develops nonlinear orientation as in the corresponding linear polymer, whereas long-arm retraction subsequently relaxes the stored branch-point tension and progressively erases backbone orientational memory. This competition produces a characteristic NLI maximum followed by a post-peak decay. The theory predicts two distinct nonlinear regimes corresponding to sparse and dense long-chain branching and introduces an architecture parameter governing the height and width of the nonlinear peak. The resulting framework provides a molecular interpretation of nonlinear Fourier rheology and directly links the nonlinear harmonic response to polymer architecture.
